they just have one hockey team. Other sports are popular in Canada but hockey dominates more than any one sport in the US. New York, LA are bigger but their big sports have multiple teams in the area (Yankees/Mets, Lakers/Clippers, etc) to siphon off some of the attention. So to other Canadian fans it feels like hockey news is very Leaf-centered (which it is) even though the quality of the team never merits it (which is true). Also there’s just a ton of fans so everyone knows that guy from work or school who is a big Leafs fan. I can’t hate the Winnipeg Jets fans if I’ve never met one.
So a good comparison is maybe the Yankees without the winning... so maybe the Knicks?